Semiconductor device and method of controlling the same

ABSTRACT

A semiconductor device includes a regulator including an operational amplifier configured of a current mirror and generating the second voltage V 2  from a first voltage V 1 ; and a control circuit that generates the current control signal OVDR, makes a current that is flowed by the current mirror increase by a first transition of the current control signal OVDR, and makes the current that is flowed by the current mirror decrease by a second transition of the current control signal OVDR. The control circuit includes a slew-rate processing unit that makes a second slew rate of the current control signal OVDR related to the second transition be smaller than a first slew rate of the current control signal OVDR related to the first transition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method ofcontrolling the same, and particularly relates to a semiconductor devicethat generates an internal voltage from an external power supply voltageand a method of controlling the same.

2. Description of Related Art

In some of the semiconductor devices such as a DRAM (Dynamic RandomAccess Memory), two regulators are employed in an internal voltagegenerating circuit which generates an internal voltage from an externalpower supply voltage. One of them is a stand-by regulator whose currentsupply capability is small and a power consumption is also small, andanother one of them is an active regulator whose current supplycapability and power consumption are both large. Such a configuration isemployed primarily from a viewpoint of reducing the power consumption,where the stand-by regulator is configured to operate constantly duringwhen a power of the semiconductor device is on, whereas the activeregulator is configured to operate only during an active period.

A regulator is generally configured by including an operationalamplifier and a driver transistor. An activation of the active regulatoris performed by turning on a current supplying transistor provided in acommon source of the operational amplifier. When the current supplyingtransistor is turned on, a current flows in a current mirror circuit inthe operational amplifier and thereby the driver transistor turns on,and the internal voltage begins to be generated. Japanese PatentApplication Laid-open Nos. H05-62481, 2001-84765 and H11-96758 discloseexamples of a voltage generating circuit that performs such anactivation control.

In the voltage generating circuit described in Japanese PatentApplication Laid-open No. H05-62481, two current supplying transistorsare provided in parallel, and one of the current supplying transistorsis configured to turn on only for a predetermined period of time upon aswitchover from a stand-by to being active. By employing such aconfiguration, as is described in paragraph [0007] of Japanese PatentApplication Laid-open No. H05-62481, it becomes possible to suppress adrop in the internal voltage just after the switchover as possible, andalso to suppress an overshoot in the internal voltage due to a reactionafter the drop.

However, in the aforementioned configuration, there is a problem thatanother overshoot (in a case where the driver transistor is an N-typechannel MOS transistor) or an undershoot (in a case where the drivertransistor is a P-type channel MOS transistor) occurs in the internalvoltage just after the one of the current supplying transistors isturned off. This is because a gate potential of the driver transistortemporarily rises due to the current supplying transistor being abruptlyturned off, and a suppression of such an overshoot or an undershoot isbeing required.

SUMMARY

In one embodiment, there is provided a semiconductor device thatincludes: an internal voltage generating circuit supplied with a firstvoltage to generate a second voltage and including an operationalamplifier having a current mirror circuit; and a control circuit thatgenerates a current control signal, wherein the current mirror circuitincreases an operating current thereof in response to a first transitionof the current control signal and decreases the operating current inresponse to a second transition of the current control signal, and thecontrol circuit includes a slew-rate processing unit that controls aslew-rate of the current control signal so that a first slew rate of thecurrent control signal related to the first transition is greater than asecond slew rate of the current control signal related to the secondtransition.

In another embodiment, there is provided a semiconductor device thatincludes: an internal voltage generating circuit including adifferential amplifier having first and second input nodes and an outputnode, first and second current supplying transistors connected inparallel to the differential amplifier to supply an operating current tothe differential amplifier, and a driver transistor having a controlelectrode and first and second controlled electrodes, the firstcontrolled electrode of the driver transistor being supplied with afirst voltage, the second controlled electrode of the driver transistorbeing connected to the second input node of the differential amplifier,the control electrode of the driver transistor being connected to theoutput node of the differential amplifier, the first input node of thedifferential amplifier being supplied with a target voltage of a secondvoltage to be generated, thereby the second voltage is output from thesecond controlled electrode of the driver transistor; and a controlcircuit that generates an current control signal based on an activesignal indicating an activate period of the internal voltage generatingcircuit, the current control signal being activated for a predeterminedperiod in response to a start of the activate period, wherein the activesignal is supplied to a control electrode of the first current supplyingtransistor, the current control signal is supplied to a controlelectrode of the second current supplying transistor, and the controlcircuit includes a slew-rate processing unit that makes a slew rate ofthe current control signal upon an inactivation thereof be smaller thana slew rate of the active signal upon an activation or an inactivationthereof.

Instill another embodiment, there is provided a method of controlling asemiconductor device that includes: providing the semiconductor devicecomprising an internal voltage generating circuit including anoperational amplifier having a current mirror circuit, the internalvoltage generating circuit receiving a first voltage to generate asecond voltage; increasing an operating current flowing to the currentmirror circuit by activating a current control signal at a first slewrate; and decreasing the operating current flowing to the current mirrorcircuit by inactivating the current control signal at a second slewrate, wherein the second slew rate is smaller than the first slew rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for explaining a principle of the presentinvention;

FIG. 2 is a block diagram showing a configuration of the semiconductordevice according to a preferred first embodiment of the presentinvention;

FIG. 3 is a block diagram showing a V_(PERI) generating circuit thatgenerates the internal voltage V_(PERI) extracted from among the circuitblocks included in the power supply circuit and also describes thetarget voltage generating circuit, the DLL circuit, and a phasecompensating circuit;

FIG. 4 is a circuit diagram specifically showing an internalconfiguration of the operational amplifier and the driver circuitaccording to the preferred first embodiment of the present invention;

FIG. 5 is a circuit diagram specifically showing an internalconfiguration of the slew rate processing unit and the one-shot signalgenerating unit according to the preferred first embodiment of thepresent invention;

FIG. 6 is a diagram showing changes of the active signal ACT, theone-shot signal P and the current control signal OVDR over timeaccording to the preferred first embodiment of the present invention;

FIG. 7 is a diagram showing a change in the power supply voltageV_(PERI) generated by the V_(PERI) generating circuit according to thepreferred first embodiment of the present invention over time, and adiagram showing changes of the active signal ACT and the current controlsignal OVDR over time;

FIG. 8 is a circuit diagram specifically showing an internalconfiguration of a slew rate processing unit included in a semiconductordevice according to a first modification of the first embodiment;

FIG. 9 is a circuit diagram specifically showing internal configurationsof the operational amplifier 61 and the driver circuit included in theV_(PERI) generating circuit 2 included in a semiconductor deviceaccording to a second modification of the first embodiment;

FIG. 10 is a block diagram showing a semiconductor device according to apreferable second embodiment of the present invention;

FIG. 11A is a diagram schematically depicting a circuit diagram of thesemiconductor device according to the preferable second embodiment ofthe present invention;

FIG. 11B is a diagram schematically depicting a circuit diagram of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 12 is a block diagram showing a configuration of a semiconductordevice of a third preferable embodiment of the present invention;

FIG. 13 is a diagram showing a result of a measurement of a frequencyproperty in an amount of noise superposed with the power supply voltageV_(PERI) in the third and a fourth preferable embodiment of the presentinvention; and

FIG. 14 is a block diagram showing a configuration of the V_(PERI)generating circuit included in the semiconductor device according to thefourth preferable embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A representative example of the technical concept of the presentinvention for solving the events will be described below. It will beunderstood that what is claimed by the present invention is not limitedto such a technical concept and is set forth in the claims of thepresent invention. That is, a technical concept of the present inventionis as follows: In regards to a current to be flowed in a current mirrorof an operational amplifier included in a first internal voltagegenerating circuit that generates a second voltage from a first voltage,the present invention makes a slew rate upon decreasing the current besmaller than a slew rate upon increasing the current. More specifically,the first internal voltage generating circuit is a circuit that isactivated responsive to an active signal, and the first internal voltagegenerating circuit makes slew rate upon an inactivation of an currentcontrol signal which is activated for a predetermined period of time inresponse to the activation of the active signal be smaller than its slewrate upon the activation. Due to this, since a temporal rise in anoutput voltage of the operational amplifier upon the current flowing inthe current mirror decreasing by the inactivation of the current controlsignal can be suppressed, the overshoot or the undershoot can besuppressed.

Referring now to FIG. 1, a semiconductor device 1 of the presentinvention is provided with a regulator 6 (first internal voltagegenerating circuit) that generates a second voltage V₂ from a firstvoltage V₁ (V₂<V₁). The first voltage V₁ is typically an externalvoltage. Although not shown, the second voltage V₂ is supplied to apredetermined load in the semiconductor device 1 via an internal powersupply line.

The regulator 6 includes an operational amplifier 61 and a drivercircuit 65. The operational amplifier 61 includes a differentialamplifier 62 configured of a current mirror, and a target voltageV_(REF) of the second voltage V₂ is supplied to one of input terminalsof the differential amplifier 62 from a target voltage generatingcircuit 3. The driver circuit 65 is a driver transistor, and the firstvoltage V₁ is supplied to one of its controlled terminals, and a controlterminal and another one of the controlled terminals are connected to anoutput terminal of the differential amplifier 62 and another one of theinput terminals of the differential amplifier 62, respectively. Thedriver circuit 65 may be an N-type channel, or may be a P-type channel.An output voltage V₂ of the regulator 6 is taken out from the other ofthe controlled terminals of the driver circuit 65. According to theaforementioned configuration, the operational amplifier 61 performs anon/off control of the driver circuit 65 such that the voltage V₂ of theother of the controlled terminals of the driver circuit 65 equals thetarget voltage V_(REF). Consequently, the output voltage V₂ of theregulator 6 becomes equal to the target voltage V_(REF). Note that, “on”herein refers to being electrically conductive, and “off” herein refersto being electrically nonconductive. These apply herein to the presentspecification.

The on/off control as aforementioned by the operational amplifier 61 isnot performed constantly; it is performed only in a case where an activesignal ACT is in an active state. The active signal ACT is a signalindicating an active period of the regulator 6, i.e. a period duringwhen a generating operation of the second voltage V₂ by the regulator 6is required, and is generated outside the regulator 6. A switchover ofthe operational state of the operational amplifier 61 by the activesignal ACT is performed by using first and second current supplyingtransistors 63, 64 provided in the operational amplifier 61.

The first and second current supplying transistors 63, 64 aretransistors that supply a current to the differential amplifier 62, andare provided in parallel between the differential amplifier 62 and aground potential. When one or both of the first and second currentsupplying transistors 63, 64 are turned on, the current flows in thedifferential amplifier 62, and the aforementioned on/off control by theoperational amplifier 61 is performed.

The active signal ACT is input to a control terminal of the firstcurrent supplying transistor 63. Consequently, the first currentsupplying transistor 63 is constantly turned on during the active periodof the regulator 6, and thereby the output voltage V₂ of the regulator 6is maintained at the target voltage V_(REF).

On the other hand, a current control signal OVDR from a control circuit8 is input to a control terminal of the second current supplyingtransistor 64. The current control signal OVDR is a signal that isactivated for a predetermined period in response to a start of theactive period of the regulator 6. Consequently, the second currentsupplying transistor 64 is temporarily turned on at the beginning of theactive period of the regulator 6. While the second current supplyingtransistor 64 is turned on, since the amount of the current flowing inthe differential amplifier 62 is increased by a corresponding amount, itbecomes possible to suppress a temporal drop in the second voltage V₂just after the activation of the active signal ACT. Further, a temporalrise (overshoot) in the second voltage V₂ due to a reaction after thedrop can also be suppressed. According to these, an effect can beachieved in which a time (setting time) after the activation of theregulator 6 until the second voltage V₂ comes to be generated stably canbe shortened. Further, in assuming that the second current supplyingtransistor 64 had continuously been kept on during the activation periodof the regulator 6, a problem that a power consumption of a chip as awhole becomes large would occur, however, by limiting the period of theturn-on to be within the predetermined period during the switchover fromthe stand-by to being activated, such an increase can be suppressed.

The control circuit 8 generates the current control signal OVDR based onthe active signal ACT. Specifically, the control circuit 8 activates thecurrent control signal OVDR at an activating timing of the active signal(first transition), and after a certain period of time has elapsed,deactivates the current control signal OVDR (second transition).

The feature of the present invention is that the control circuit 8includes a slew rate processing unit 80 that processes a slew rate(amount of change per a given time) of the current control signal OVDRupon its inactivation (second transition). The slew rate processing unit80 makes a slew rate (second slew rate) of a current control signal OVDRrelated to the inactivation (second transition) to be smaller than aslew rate (first slew rate) of a current control signal OVDR related tothe activation (first transition). From a different point of view, itmay alternatively be said that the slew rate processing unit 80 makesthe slew rate of the current control signal OVDR upon its inactivation(second slew rate) be smaller compared to the slew rate of the activesignal ACT upon its activation or inactivation.

When the second current supplying transistor 64 is abruptly turned off,a potential of the control terminal of the driver circuit 65 risestemporarily. Due to this, an overshoot (in the case where the drivercircuit 65 is the N-type channel) or an undershoot (in the case wherethe driver circuit 65 is the P-type channel) is exhibited in the secondvoltage V₂. In the present invention, since the temporal rise in thepotential of the control terminal of the driver circuit 65 is suppressedby the aforementioned processing of the slew rate processing unit 80,the occurrence of such overshoot or undershoot is suppressed.

Preferred embodiments of the present invention will be explained belowin detail with reference to the accompanying drawings.

Turning to FIG. 2, the semiconductor device 1 of the present embodimentis a DRAM, and includes a memory cell array 11 as shown in FIG. 2. Inthe memory cell array 11, a plurality of word lines WL and a pluralityof bit lines BL that intersect one another are provided, and memorycells MC are arranged at interunits thereof. A selection of the wordlines WL is performed by a row decoder 12, and a selection of the bitlines BL is performed by a column decoder 13. Each bit line BL isconnected to a corresponding sense amplifier SA in a sense circuit 14,and the bit line BL selected by the column decoder 13 is connected to anamplifier circuit 15 via the sense amplifier SA.

Operations of the row decoder 12 and the column decoder 13 arecontrolled by an access control circuit 20. The access control circuit20 receives an address signal ADD and a command signal CMD supplied fromoutside via an address terminal 21 and a command terminal 22,respectively, and controls the row decoder 12 and the column decoder 13based on these address signal ADD and command signal CMD. Further, theaccess control circuit 20 also controls an operation of the amplifiercircuit 15.

Specifically, in a case where the command signal CMD indicates an activeoperation, the address signal ADD is supplied to the row decoder 12. Inresponse to this, the row decoder 12 selects a word line WL indicated bythe address signal ADD, and thereby corresponding memory cells MC arerespectively connected to the bit lines BL. Further, in a case where thecommand signal CMD indicates a read operation or a write operation, theaddress signal ADD is supplied to the column decoder 13. In response tothis, the column decoder 13 connects a bit line BL indicated by theaddress signal ADD to the amplifier circuit 15. Consequently, in thecase where the command signal CMD indicates the read operation, readdata DQ read from the memory cell array 11 via the sense amplifiers SAis output to outside from a data terminal 24 via the amplifier circuit15 and an input/output circuit 16. On the other hand, in the case wherethe command signal CMD indicates the write operation, write data DQsupplied from outside via the data terminal 24 is written into thememory cells MC via the input/output circuit 16, the amplifier circuit15, and the sense amplifiers SA.

The aforementioned respective circuit blocks use predetermined internalvoltages as their operation power source. These internal voltages aregenerated by a power supply circuit 100 shown in FIG. 2. The powersupply circuit 100 receives an external potential V_(DD) and a groundpotential V_(SS) supplied respectively via power supply terminals 31,32, and generates internal voltages V_(PP), V_(PERI), V_(ARY), etc.based on the potentials. Note that, in this specification, V_(DD),V_(PP), V_(PERI), and V_(ARY) indicate levels of the potentials, and inaddition, also indicate potential differences (voltages) relative to theground potential V_(SS). For example, “V_(DD)” refers to the potentiallevel itself of the external potential V_(DD), and also indicates thepotential difference (voltage) relative to the ground potential V_(SS).The same applies to V_(PP), V_(PERI), and V_(ARY). In the presentembodiment, V_(PP)>V_(DD)>V_(PERI)≈V_(ARY).

The internal voltage V_(PP) is a voltage used in the row decoder 12. Therow decoder 12 drives the word line WL selected based on the addresssignal ADD at the V_(PP) level, and thereby makes cell transistorsincluded in the memory cells MC turn on. The internal voltage V_(ARY) isa voltage used in the sense circuit 14. The sense circuit 14, whenactivated, amplifies read data that has been read by driving one of abit line pair at the V_(ARY) level and another one thereof at the V_(SS)level. The internal voltage V_(PERI) is used as an operational voltagefor most of peripheral circuits such as the access control circuit 20.In the circuits that operate with the internal voltage V_(PERI) as theoperational power supply, a DLL circuit 4 that generates an internalclock for synchronizing an output timing of data by the input/outputcircuit 16 with an external clock input from a clock terminal 23 isincluded. By using the internal voltage V_(PERI) having a lower voltagethan V_(DD) as the operational voltage of the peripheral circuits, areduction of the power consumption is realized.

Aside from the V_(PERI) generating circuit 2, FIG. 3 also describes thetarget voltage generating circuit 3, the DLL circuit 4, and a phasecompensating circuit 5. Prior to an explanation on the V_(PERI)generating circuit 2, these circuits will be explained.

The target voltage generating circuit 3 is a circuit that generates thetarget voltage V_(REF) of the power supply voltage V_(PERI), and isherein a constant voltage generating circuit. Specifically, the targetvoltage generating circuit 3 may be configured by a circuit that takesout the target voltage V_(REF) by dividing the power supply voltageV_(DD) using a resistance. The generation scheme of the target voltageV_(REF) by a resistance division is called a voltage generating scheme.Meanwhile, although a scheme called a current generating scheme may beemployed for the generation of the target voltage V_(REF), this featurewill be explained in detail in a second embodiment described later.

The DLL circuit 4 denotes an example of the peripheral circuits thatoperate with the power supply voltage V_(PERI) as the operational powersource. The DLL circuit 4 is a circuit that generates the internal clockonly when an output of the read data is performed, and is in a sleepstate in cases where the output of the read data is not performed.Consequently, the current consumption of the DLL circuit 4 greatlyvaries depending on whether the output of the read data is performed ornot.

The phase compensating circuit 5 is a serial circuit of a resistiveelement and a capacity element, and is connected in parallel with theDLL circuit 4 between a V_(PERI) output terminal 2 a (described later)and a ground terminal. The phase compensating circuit 5 is provided tostabilize a waveform of the power supply voltage V_(PERI).

An explanation of the V_(PERI) generating circuit 2 will be given below.As shown in FIG. 3, the V_(PERI) generating circuit 2 includes an activeregulator 6 (first internal voltage generating circuit), a stand-byregulator 7 (second internal voltage generating circuit), and thecontrol circuit 8.

The regulators 6, 7 generate the power supply voltages V_(PERI) for theperipheral circuits respectively from the power supply potential V_(DD),and output the same to the V_(PERI) output terminal 2 a. The V_(PERI)output terminal 2 a is connected to a power supply terminal of the DLLcircuit 4, and the power supply voltage V_(PERI) is supplied to the DLLcircuit 4 thereby. The regulator 6 generates the power supply voltageV_(PERI) in response to the active signal ACT only when needed asdescribed above, while on the other hand, the regulator 7 constantlygenerates the power supply voltage V_(PERI) during when at least thepower of the semiconductor device 1 is on.

The active signal ACT is a signal that is activated e.g. when the outputof the read data is performed. As described above, the DLL circuit 4generates the internal clock only when the output of the read data isperformed, and the current consumption of the DLL circuit 4 increases atsuch an occasion. The active signal ACT is activated when the output ofthe read data is performed so that this increased current consumptioncan sufficiently be dealt with, and makes the current supply capabilityof the V_(PERI) generating circuit 2 be increased. That is, in the casewhere the active signal ACT is in the active state, since both of theregulators 6, 7 generate the power supply voltage V_(PERI), the currentsupply capability of the V_(PERI) generating circuit 2 is increasedcompared to a case where only the regulator 7 generates the power supplyvoltage V_(PERI).

Next, as shown in FIG. 3, the regulator 6 includes the operationalamplifier 61 and the driver circuit 65. The operational amplifier 61includes the differential amplifier 62 configured of the current mirror,and the target voltage V_(REF) of the power supply voltage V_(PERI) issupplied to one of input terminals of the differential amplifier 62 fromthe target voltage generating circuit 3. Further, the first and secondcurrent supplying transistors 63, 64 are provided in parallel betweenthe differential amplifier 62 and the ground potential. The drivercircuit 65 is a driver transistor, and the power supply voltage V_(PERI)is supplied to the one of its controlled terminals, and the controlterminal and the other of the controlled terminals are connected to theoutput terminal of the differential amplifier 62 and the other of theinput terminals of the differential amplifier 62, respectively.

Turning to FIG. 4, the differential amplifier 62 includes P-type channeltransistors M1, M2 configuring a current mirror, an N-type channeltransistor M3 having a drain connected to a drain of the transistor M1,and an N-type channel transistor M4 having a drain connected to a drainof the transistor M2. The driver circuit 65 is configured of an N-typechannel transistor M5.

The power supply voltage V_(PP) (>V_(DD)) is supplied to sources of thetransistors M1, M2, and the target voltage V_(REF) is supplied to a gateof the transistor M3 (the one of the input terminals of the differentialamplifier 62). The reason of supplying the power supply voltage V_(PP)higher than the power supply voltage V_(DD) to the sources of thetransistors M1, M2 is to prevent the power supply voltage V_(PERI) to begenerated from becoming lower than the target voltage V_(REF) due to thevariation in the power supply voltage V_(DD). Hereinbelow, a detailedexplanation will be given.

In the regulator 6, since the driver circuit 65 is configured of thetransistor M5 that is the N-type channel, when assuming that the powersupply voltage supplied to the sources of the transistors M1, M2 asV_(XX) (V_(XX) being V_(PP) or V_(DD)), the maximum value of thegeneratable power supply voltage V_(PERI) comes to be V_(XX)−Vt. Notethat Vt is a threshold voltage of the transistor M5. A differencebetween this maximum value and the target voltage V_(REF) isV_(XX)−Vt−V_(REF), and in order to maintain the power supply voltageV_(PERI) at the target voltage V_(REF), this difference must be 0 ormore. That is, V_(XX)≧Vt+V_(REF) is necessary to maintain the powersupply voltage V_(PERI) at the target voltage V_(REF).

The power supply voltage V_(DD) normally satisfies V_(DD)≧Vt+V_(REF).However, there is a possibility that the power supply voltage V_(DD)varies due to a variation in the external power supply. etc., anddepending on the amount of the variation, V_(DD)≧Vt+V_(REF) may not besatisfied. Thus, in the present embodiment, the power supply voltageV_(PP) higher than the power supply voltage V_(DD) is supplied to thesources of the transistors M1, M2 so that V_(XX)≧Vt+V_(REF) can be morecertainly satisfied.

Notably, a gate of the transistor M4 (the other of the input terminalsof the differential amplifier 62) and a source of the transistor M5 (theone of the controlled terminals of the driver circuit 65) are bothconnected to the V_(PERI) output terminal 2 a. The power supply voltageV_(DD) is supplied to a drain of the transistor M5 (the other of thecontrolled terminals of the driver circuit 65). A drain of thetransistor M2 (the output terminal of the differential amplifier 62) anda gate of the transistor M5 (the control terminal of the driver circuit65) are connected to one another.

Sources of the transistors M3, M4 are connected to one another, and areconnected to the ground terminal via N-type channel transistors M6, M7.The transistors M6, M7 are the first and second current supplyingtransistors 63, 64, respectively, and are connected in parallel betweenthe sources of the transistors M3, M4 (common source) and the groundterminal. The active signal ACT and the current control signal OVDR arerespectively input to respective one of gates of the transistors M6, M7.Note that the active signal ACT and the current control signal OVDR arehigh-active signals.

According to the above configuration, during when the active signal ACTis activated, currents equivalent to one another flow in the transistorsM1, M2 configuring the current mirror, and due to this, the potential ofthe V_(PERI) output terminal 2 a is maintained at the target voltageV_(REF). To explain in further detail, in a case where the potential ofthe V_(PERI) output terminal 2 a becomes lower than the target voltageV_(REF), the current flowing in the transistor M4 decreases, and therebya common source potential of the transistors M3, M4 decreases. Then, thecurrent of the transistor M3 increases, which induces the current of thetransistor M1 to increase. Since the transistors M1, M2 configure thecurrent mirror, the current of the transistor M2 also increases. Due tothis, the gate potential of the transistor M5 rises, and the currentsupplied to the V_(PERI) output terminal 2 a via the transistor M5increases. Due to this, the potential of the V_(PERI) output terminal 2a shifts to an increasing direction. On the other hand, in a case wherethe potential of the V_(PERI) output terminal 2 a becomes larger thanthe target voltage V_(REF), the current flowing in the transistor M4increases, and thereby the common source potential of the transistorsM3, M4 rises. Then, the current of the transistor M3 decreases, whichinduces the current of the transistor M1 to decrease. Since thetransistors M1, M2 configure the current mirror, the current of thetransistor M2 also decreases. Consequently, the gate potential of thetransistor M5 drops, and the current supplied to the V_(PERI) outputterminal 2 a via the transistor M5 decreases. Due to this, the potentialof the V_(PERI) output terminal 2 a shifts to a decreasing direction.

When the current control signal OVDR is activated along with theactivation of the active signal ACT, the amount of the currents flowingin the transistors M1 to M4 increases. Consequently, the differentialamplifier 62 is enabled to operate even faster, and it becomes possibleto suppress the temporal drop in the power supply voltage V_(PERI) justafter the activation of the active signal ACT. Further, the temporalrise (overshoot) in the power supply voltage V_(PERI) due to thereaction after the drop can also be suppressed.

On the other hand, when the current control signal OVDR is inactivatedduring when the active signal ACT is in the active state, the amount ofthe currents flowing in the transistors M1 to M4 decreases by acorresponding amount. Note that, for some period of time, since agate-source voltages of the transistors M1, M2 are maintained at valuesat the beginning of the activation of the current control signal OVDR,an imbalance in the currents occurs in the transistors M1, M2 and thetransistors M3, M4 during that time, and drain voltages of thetransistors M1, M2 rise. The gate potential of the transistor M5 risesaccompanying this rise, and just after the start of the inactivation ofthe current control signal OVDR, it becomes the cause of the significanttemporal rise in the power supply voltage V_(PERI) beyond the targetvoltage V_(REF). In the semiconductor device 1 of the presentembodiment, since the slew rate upon the inactivation of the currentcontrol signal OVDR is made smaller than usual, it is possible tosuppress the overshoot of the power supply voltage V_(PERI) just afterwhen the inactivation of the current control signal OVDR is started.Details thereof will be explained later in detail.

The explanation will return to FIG. 3. As shown in FIG. 3, the controlcircuit 8 includes the slew rate processing unit 80 and a one-shotsignal generating unit 81. The one-shot signal generating unit 81generates a one-shot signal P that is activated for a predeterminedperiod of time in response to the activation of the active signal ACT.The slew rate processing unit 80 generates a current control signal OVDRhaving a slew rate upon its inactivation that is smaller than a slewrate upon its activation by making the slew rate of the one-shot signalP upon the inactivation be small. The current control signal OVDR isinput to the control terminal of the second current supplying transistor64 as aforementioned.

Turning to FIG. 5, the one-shot signal generating unit 81 is configuredby including a delay line 82, an inverter 83, and a NAND circuit 84, andthe slew rate processing unit 80 is configured by including a complementtype transistor configured of a P-type channel transistor M10 and anN-type channel transistor M11, a resistive element 86, and a capacityelement 87 (first capacity element). The current control signal OVDR isoutput from an output terminal 80 a via an internal line 80 b of theslew rate processing unit 80. A source terminal of the P-type channeltransistor M10 is connected to a first node where the power supplyvoltage V_(DD) is supplied. A source terminal of the N-type channeltransistor M11 is connected to a second node where the ground voltage issupplied via the resistive element 86. A drain terminal of the P-typechannel transistor M10 and a drain terminal of the N-type channeltransistor M11 are connected to the internal line 80 b. One of terminalsof the capacity element 87 is connected to the internal line 80 b, andanother one of its terminals is connected to the second node.

Turning to FIG. 6, the horizontal axis denotes time, and the verticalaxis denotes voltage. Hereinbelow, operations of the slew rateprocessing unit 80 and the one-shot signal generating unit 81 will beexplained in detail with reference to this FIG. 6 as well.

As shown in FIG. 5, the active signal ACT is input to the delay line 82.As shown in FIG. 6, the active signal ACT is a high-active signal(signal that becomes high during the activation period). The slew ratesof the active signal ACT upon the activation and the inactivation aresubstantially infinite as shown in FIG. 6. The delay line 82 delays theinput active signal ACT for a certain period of time tw, and inputs thesame to the inverter 83. The inverter 83 inverts the delayed signalinput from the delay line 82, and inputs the same to the NAND circuit84.

In addition to the aforementioned delayed signal, the active signal ACTthat is not delayed is also input to the NAND circuit 84. Consequently,as shown in FIG. 6, the output of the NAND circuit 84 becomes alow-active one-shot signal P which activates at the activating timing ofthe active signal ACT and inactivates at a timing when the certainperiod of time tw has elapsed.

The one-shot signal P is input to an input terminal of the complementtype transistor configured of the transistors M10, M11. The power supplyvoltage V_(DD) is supplied to the source of the transistor M10, and thesource of the transistor M11 is connected to the ground terminal via theresistive element 86. Further, an output terminal of the complement typetransistor is connected to the line 80 b. Consequently, when theone-shot signal P is low (active state), the power supply voltage V_(DD)is supplied to the line 80 b, and the potential of the output terminal80 a comes to be at the power supply voltage V_(DD). On the other hand,when the one-shot signal P is high (inactive state), the line 80 b isconnected to the ground terminal, and the potential of the outputterminal 80 a comes to be at the ground potential V_(SS).

The capacity element 87 is connected between the line 80 b and theground terminal. Consequently, when the one-shot signal P becomes lowand the power supply voltage V_(DD) begins to be supplied to the line 80b, charging of the capacity element 87 is started. On the other hand,when the one-shot signal P becomes high and the line 80 b is connectedto the ground terminal via the resistive element 86, charges that hadbeen accumulated in the capacity element 87 begins to be discharged. Thespeed of this discharge is determined by the electric capacitance of thecapacity element 87 and the resistance value of the resistive element86. Note that, it is sufficient that the resistive element 86 and thecapacity element 87 are connected in series between two ground terminalsand the line 80 b is connected between these two elements. It goeswithout saying that an order of the resistive element 86 and thecapacity element 87 is not limited. Further, a structure and material ofthe resistive element 86 is not limited.

By the discharge of the capacity element 87 as aforementioned beingperformed, the potential of the output terminal 80 a does not drop tothe ground potential V_(SS) abruptly even if the one-shot signal Pbecomes high. In other words, by the processing of the slew rateprocessing unit 80, the slew rate of the current control signal OVDRupon the inactivation is changed to be smaller than the usual slew rate(slew rate of the active signal ACT upon its activation or inactivation,or slew rate of the current control signal OVDR upon its activation) asshown in FIG. 6. Accordingly, by the processing of the slew rateprocessing unit 80, the slew rate of the current control signal OVDRupon the inactivation can be made smaller than usual.

Hereinbelow, an effect of making the slew rate of the current controlsignal OVDR upon the inactivation smaller than usual will be explainedin detail.

An upper diagram of FIG. 7 is a diagram showing a change in the powersupply voltage V_(PERI) generated by the V_(PERI) generating circuit 2over time, and a lower diagram thereof is a diagram showing changes ofthe active signal ACT and the current control signal OVDR over time. Inthese drawings, the horizontal axes denote time, and the vertical axesdenote voltage. In the upper diagram, a case in which the currentcontrol signal OVDR is not used (a case in which the second currentsupplying transistor 64 is not provided), and a case in which the slewrate processing upon the inactivation is not performed are described ascomparative examples. In the lower diagram, the current control signalOVDR in the case where the slew rate processing upon an inactivation isnot performed is also shown.

As is apparent in the lower diagram of FIG. 7, the slew rate of thecurrent control signal OVDR upon the inactivation is lowered by theprocessing of the slew rate processing unit 80. A magnitude of thedecrease is preferably set such that the time (descending time) tf untilthe current control signal OVDR returns to low becomes longer than theactivation period tw of the one-shot signal P. For example, in a casewhere the regulator 6 is formed by a minimum process dimension of 45 nm,since the optimal value of the activation period tw becomes 10 nsec, thedescending time tf is preferably determined as a value larger than 10nsec. The setting of the magnitude of the slew rate can be performed byappropriately adjusting the resistance value of the resistive element 86and the capacitance value of the capacity element 87 as shown in FIG. 5.

As shown in the upper diagram of FIG. 7, in the case of not using thecurrent control signal OVDR, the power supply voltage V_(PERI) drops byabout 70 mV just after the activation of the active signal ACT, andthereafter gradually approaches the target voltage V_(REF). After havingreached the target voltage V_(REF), it once greatly exceeds the targetvoltage V_(REF) (overshoots), and then converges to the target voltageV_(REF) gradually while fluctuating.

On the other hand, in the case of using the current control signal OVDRto which the slew rate processing upon the inactivation is notperformed, the drop of the power supply voltage V_(PERI) just after theactivation of the active signal ACT is suppressed to about 40 mV.Further, an overshoot such as in the case of not using the currentcontrol signal OVDR does not occur. However, on the other hand, as shownin the upper diagram in FIG. 7, another overshoot occurs just after theinactivation of the current control signal OVDR is started. After theoccurrence of this overshoot, similar to the case of not using thecurrent control signal OVDR, the voltage converges to the target voltageV_(REF) gradually while fluctuating.

By performing the slew rate processing of the slew rate processing unit80, as shown in the upper diagram in FIG. 7, the overshoot just afterthe start of the inactivation of the current control signal OVDR issuppressed. This is due to the temporal rise in the drain voltage of thetransistors M1, M2 shown in FIG. 4 being suppressed by performing theinactivation of the current control signal OVDR against time.Hereinbelow, a detailed explanation will be given.

The gates of the transistors M1, M2 configure a capacitance, and duringwhen the current control signal OVDR is activated, larger charge isaccumulated in this capacitance than in the case where the currentcontrol signal OVDR is inactivated. In other words, the gate-sourcevoltage of the transistors M1, M2 becomes larger than in the case wherethe current control signal OVDR is inactivated. The large gate-sourcevoltages are maintained for a while even after the start of theinactivation of the current control signal OVDR, and during that time,the current flowing in the transistor M2 temporarily becomes larger thanthe current flowing in the transistor M4. This causes the gate potentialof the transistor M5 to rise, and causes the aforementioned overshoot.If the slew rate processing of the slew rate processing unit 80 isperformed, since the current flowing in the transistor M4 slowly becomessmall, an increase in a difference between the current flowing in thetransistor M2 and the current flowing in the transistor M4 issuppressed. Consequently, the overshoot of the power supply voltageV_(PERI) just after the start of the inactivation of the current controlsignal OVDR is suppressed.

As explained above, according to the semiconductor device 1 of thepresent embodiment, it becomes possible to suppress the overshoot of thepower supply voltage V_(PERI) just after the start of the inactivationof the current control signal OVDR.

Further, by the overshoot being suppressed, an effect can be achieved inwhich a required time (setting time) from when the active signal ACT isactivated until when the power supply voltage V_(PERI) converges to thetarget voltage V_(REF) is shortened.

Here, in a case where the DLL circuit 4 is used e.g. in a DRAM of a DDR(Double-Data-Rate) 3 type, the setting time needs to be within 24 nsec.If the setting time exceeds 24 nsec, an error occurs in a delayed timein the delay line (not shown) in the DLL circuit 4, and a jitter thatcannot be ignored is generated in an output of the DRAM. The settingtime may be shortened by enlarging the capacitance of the capacityelement in the phase compensating circuit 5, however, in the case oftrying to realize the setting time of 24 nsec or less without using thecurrent control signal OVDR, a large capacitance nearing 10 nF will beneeded. This means a significant increase in a chip area. Since theusage of a capacity element with such a large capacitance will not beneeded by using the current control signal OVDR, the chip area can bereduced. On the other hand, by merely using the current control signalOVDR, although smaller than 10 nF, a capacity element having a certaindegree of a large capacitance will nonetheless be needed. According tothe semiconductor device 1 of the present embodiment, by performing theslew rate processing by the slew rate processing unit 80, the settingtime can further be shortened, thus the capacitance of the capacityelement in the phase compensating circuit 5 can further be made small.

Turning to FIG. 8 the semiconductor device 1 of the present modificationdiffers from the semiconductor device 1 of the first embodiment in thatthe slew rate processing unit 80 includes a constant current circuit 88instead of the resistive element 86. Other features are identical tothose of the semiconductor device 1 of the first embodiment.

The constant current circuit 88 is configured by including an N-typechannel transistor M12 that is connected between a source of atransistor M11 and the ground terminal, an N-type channel transistor M13connected between a power supply line through which the power supplyvoltage V_(YY) is supplied and the ground terminal, and a resistiveelement 89 inserted between the power supply line through which a powersupply voltage V_(YY) is supplied and the transistor M13. The powersupply voltage V_(YY) is preferably determined as one of the powersupply voltage V_(DD) and the power supply voltage V_(PERI). Thetransistors M12, M13 configure a current mirror, and a ratio (mirrorratio) of a value of a current flowing in the transistor M12 to a valueof a current flowing in the transistor M13 is m. According to theseconfigurations, a constant current I flows in the transistor M12. In theslew rate processing unit 80 of the present modification, a discharge ofthe capacity element 87 is realized by this constant current I. In thiscase, the aforementioned descending time is tf=V_(YY)×C₁/I. Note that C₁is an electric capacitance of the capacity element 87.

As indicated in the above formula, in the present modification, thedischarging time of the capacity element 87 just after the inactivationof the one-shot signal P can be adjusted alternatively by the currentvalue of the constant current I. The adjustment of the current value ofthe constant current I may be performed either by determining the powersupply voltage V_(YY) as the power supply voltage V_(DD) or the powersupply voltage V_(PERI), by adjusting the mirror ratio m, or by anadjustment of a resistance value of the resistive element 89.

According to the present modification, even if the resistance value ofthe resistive element 89 is not so large, the current value of theconstant current I can be made small. If the current value of theconstant current I is small, compared to the example of FIG. 5, withrespect to the capacity element 87, it means that an equivalentdischarge time can be secured with a smaller electric capacitance, thusit becomes possible to make an occupying area of the slew rateprocessing unit 80 in a circuit layout small.

Turning to FIG. 9, the semiconductor device 1 of the presentmodification differs from the semiconductor device 1 of the firstembodiment in that: the N-type channel transistor M5 is changed to aP-type channel transistor M8; the target voltage V_(REF) is not suppliedto the gate of the transistor M3 but to the gate of the transistor M4,and the gate of the transistor M3 is connected to the V_(PERI) outputterminal 2 a instead of the gate of the transistor M4; and the powersupply voltage to be supplied to the transistors M1, M2 is changed tothe power supply voltage V_(DD) from the power supply voltage V_(PP). Ina case where the driver circuit 65 is configured of the P-type channeltransistor M8, since the aforementioned problem accompanying thefluctuation in the power supply voltage V_(DD) does not occur, the thirdfeature is configured as above so as to supply the power supply voltageV_(DD) to the transistors M1, M2. Other features are identical to thoseof the semiconductor device 1 of the first embodiment.

As in the present modification, in the case of configuring the drivercircuit 65 with the P-type channel transistor M8, if the processing bythe slew rate processing unit 80 is not to be performed, an undershoot(drop from the target voltage V_(REF)) occurs in the power supplyvoltage V_(PERI) just after the start of the inactivation of the currentcontrol signal OVDR. This is because in the case where the gatepotential of the transistor M6 rises by the same principal as thatexplained in the first embodiment upon the current control signal OVDRbeing inactivated, an ON current of the transistor M8 that is the P-typechannel decreases contrary to the case of the N-type channel.

According to the present modification, since the current control signalOVDR that is processed by the slew rate processing unit 80 is used, therise in the gate potential of the transistor M6 just after the start ofthe inactivation of the current control signal OVDR is suppressed.Consequently, the undershoot of the power supply voltage V_(PERI) asaforementioned is suppressed.

Turning to FIG. 10, the semiconductor device 1 of the present embodimentdiffers from the semiconductor device 1 of the first embodiment in thatthe generation scheme for the target voltage V_(REF) by the targetvoltage generating circuit 3 is not the voltage generating scheme but isthe current generating scheme. Other features are identical to those ofthe semiconductor device 1 of the first embodiment, thus the samereference signals are given to the same configurational elements, anddetailed descriptions thereof are omitted.

As shown in FIG. 10, the semiconductor device 1 of the presentembodiment includes the constant current circuit 35 that generates aconstant current of a current value V_(REF)/R₁, and the resistiveelement 36 with a resistance value R₁ connected between an output of theconstant current circuit 35 and the ground terminal, and the targetvoltage generating circuit 3 is configured by these constant currentcircuit 35 and resistive element 36. That is, due to the potential ofboth terminals of the resistive element 36 becoming V_(REF), the voltageinput to the V_(PERI) generating circuit 2 as a result becomes equal toV_(REF). The constant current circuit 35 is preferably configured of aband gap reference circuit. By so doing, a noise that occurs in theoutput current V_(REF)/R₁ of the constant current circuit 35 can besignificantly decreased.

Here, respective circuits such as the V_(PERI) generating circuit 2, thetarget voltage generating circuit 3, the DLL circuit 4, etc. accordingto the present embodiment are formed in a single semiconductor chip.Consequently, the connections thereof are implemented only by wiringswithin the chip, however, for connections of the respective circuits andthe power supply lines, wirings outside the chip such as bonding wiresand lead lines of a package are used. Lines L1, L2 shown in FIG. 10indicate such wirings outside the chip that are present asaforementioned. As shown in the drawing, the constant current circuit 35and the other circuits are connected via wirings outside the chip thatare different from one another to the power supply line to which theground potential V_(SS) is supplied. By configuring as such, varioussignals flowing in the other circuits are prevented from beingsuperposed with the constant current output from the constant currentcircuit 35.

On the other hand, among circuit elements of the target voltagegenerating circuit 3, the resistive element 36 is connected via the lineL1 that is common among the V_(PERI) generating circuit 2 and the DLLcircuit 4 to the power supply line to which the ground potential V_(SS)is supplied. By configuring as such, in the semiconductor device 1 ofthe present embodiment, the operation of the DLL circuit 4 is preventedfrom becoming unstable due to the noise occurring between the wiringsoutside the chip to be superposed with the power supply voltageV_(PERI). Hereinbelow, a detailed explanation will be given.

In the example of FIG. 11B, the target voltage generating circuit 3 andthe other circuits are connected to the power supply line to which theground potential V_(SS) is supplied via the lines L1, L2 that areoutside the chip, respectively. Further, a node 4 a shown in FIGS. 11A,11B is a connecting point of the line inside the chip and the line L1outside the chip.

As shown in FIGS. 11A, 11B, between the lines outside the chip, arelatively large mutual inductance M is constituted. Since this mutualinductance M generates a noise potential Vn, a potential (referencepotential) of the node 4 a that is to be the reference of the operationof the DLL circuit 4 becomes V_(SS)′=V_(SS)+Vn, instead of V_(SS).

In the example of FIG. 11B, the target voltage V_(REF) is generated atirrelevant unit from the line L1. Consequently, the target voltage inputto the input terminal of the V_(PERI) generating circuit 2 becomesV_(REF)+Vn as seen from the reference potential V_(SS)′. Note that anoise generated in the line L2 is hereby ignored. By the noise potentialVn being superposed with the target voltage V_(REF), as shown in FIG.11B, the corresponding noise potential Vn is superposed with the powersupply voltage V_(PERI) as seen from the reference potential V_(SS)′.This becomes a cause of the operation of the DLL circuit 4 becomingunstable.

On the other hand, in the present embodiment shown in FIG. 11A, thetarget voltage V_(REF) is a potential difference between both terminalsof the resistive element 36 connected between the node 4 a and the inputterminal of the V_(PERI) generating circuit 2. Consequently, the targetvoltage input to the V_(PERI) generating circuit 2 is V_(REF) as seenfrom the reference potential V_(SS)′, and the noise potential Vn is notsuperposed therewith. Consequently, the noise potential Vn is notsuperposed with the power supply voltage V_(PERI), and the operation ofthe DLL circuit 4 is prevented from becoming unstable.

As explained above, according to the semiconductor device 1 of thepresent embodiment, the operation of the DLL circuit 4 is prevented frombecoming unstable due to the noise caused by a coupling of the linesoutside the chip being superposed with the power supply voltageV_(PERI).

Turning to FIG. 12, the semiconductor device 1 of the present embodimentdiffers from the semiconductor device 1 of the first embodiment in thata low pass filter 90 is inserted between the target voltage generatingcircuit 3 and the V_(PERI) generating circuit 2. Other features areidentical to those of the semiconductor device 1 of the firstembodiment, thus the same reference signals are given to the sameconfigurational elements, and detailed descriptions thereof are omitted.

As shown in FIG. 12, the low pass filter 90 is configured of a resistiveelement 91 having a resistance value R₁ inserted in the line connectingthe target voltage generating circuit 3 and the V_(PERI) generatingcircuit 2, and a capacity element 92 having an electric capacitance ofC₂ and connected between a node 90 a and the node 4 a. The node 90 alocates between the resistive element 91 and the V_(PERI) generatingcircuit 2. The node 4 a is a connecting point of the line inside thechip and the line L1 outside the chip as explained in the secondembodiment. A cutoff frequency fc of the low pass filter 90 becomesfc=1/(2πC₂R₁).

By employing the aforementioned low pass filter 90, in the semiconductordevice 1 of the present embodiment, it becomes possible to remove a highfrequency noise that is greater than the frequency fc from the targetvoltage V_(REF). Due to this, the high frequency noise that is greaterthan the frequency fc is prevented from being superposed with the powersupply voltage V_(PERI).

Turning to FIG. 13, although the frequency properties in the amounts ofnoise for both the power supply voltage V_(PERI) generated by using thetarget voltage V_(REF) by the voltage transmission scheme and the powersupply voltage V_(PERI) generated by using the target voltage V_(REF) bythe current transmission scheme are shown, the present embodimentfocuses on the former. As is apparent from the drawing, in thesemiconductor device 1 of the present embodiment, the high frequencynoise that is greater than the frequency fc superposed with the powersupply voltage V_(PERI) is suppressed.

Turning to FIG. 14, the semiconductor device 1 of the present embodimentdiffers from the semiconductor device 1 of the second embodiment in thatthe semiconductor device 1 of the present embodiment includes a capacityelement 94 having an electric capacitance C₂. Other features areidentical to those of the semiconductor device 1 of the secondembodiment, thus the same reference signals are given to the sameconfigurational elements, and detailed descriptions thereof are omitted.

As shown in FIG. 14, the capacity element 94 is connected in parallelwith the resistive element 36. By connecting the capacity element 94 asaforementioned, in the semiconductor device 1 of the present embodiment,the high frequency noise component superposed with the constant currentoutput from the constant current circuit 35 can be suppressed.

In referring to FIG. 13 again, in the case of generating the targetvoltage V_(REF) by the current transmission scheme, it is understoodthat noises in a relatively low frequency band are greatly suppressedfrom the first place. This is not due to the employment of the capacityelement 94, but is a property of the current transmission scheme. On theother hand, the current transmission scheme has a feature that a highnoise is superposed to the target voltage V_(REF) in a high frequencyband compared to the voltage transmission scheme. This is because theconstant current circuit 35 includes the band gap reference circuit andan amplifier that converts the voltage generated in the band gapreference circuit to a current, and the response speed of this amplifieris not so fast. In the semiconductor device 1 of the present embodiment,since the high frequency noise generated by such a reason inherent tothe current transmission scheme is removed by the capacity element 94,it becomes possible to obtain the same high frequency noise property asthe voltage transmission scheme as shown in FIG. 13.

It is apparent that the present invention is not limited to the aboveembodiments, but may be modified and changed without departing from thescope and spirit of the invention.

The technical concept of the present application may be adapted to aninternal voltage generating circuit that generates a positive voltageand a negative voltage. Further, the circuitry configurations in therespective circuit blocks disclosed in the drawings, as well as circuitsgenerating other controlled signals are not limited to the circuitryconfigurations disclosed in the present embodiments.

The technical concept of the voltage level shift circuit of the presentinvention may be applied to various semiconductor devices. For example,the present invention may be applied to semiconductor products ingeneral, including functions as CPUs (Central Processing Units), MCUs(Micro Control Units), DSPs (Digital Signal Processors), ASICs(Application Specific Integrated Circuits), ASSPs (Application SpecificStandard Products), and memories. Examples of the product types of thesemiconductor devices to which the present invention is applicableinclude an SOC (System On Chip), MCP (Multi Chip Package), and POP(Package On Package). The present invention may be applied tosemiconductor devices that have any of such product types and packagetypes.

When the transistors are field effect transistors (FETs), various FETsare applicable, including MIS (Metal Insulator Semiconductor) and TFT(Thin Film Transistor) as well as MOS (Metal Oxide Semiconductor). Thedevice may even include bipolar transistors.

In addition, an NMOS transistor (N-channel MOS transistor) is arepresentative example of a first conductive transistor, and a PMOStransistor (P-channel MOS transistor) is a representative example of asecond conductive transistor.

Many combinations and selections of various constituent elementsdisclosed in this specification can be made within the scope of theappended claims of the present invention. That is, it is needles tomention that the present invention embraces the entire disclosure ofthis specification including the claims, as well as various changes andmodifications which can be made by those skilled in the art based on thetechnical concept of the invention.

What is claimed is:
 1. A semiconductor device comprising: an internalvoltage generating circuit supplied with a first voltage to generate asecond voltage and including an operational amplifier having a currentmirror circuit; and a control circuit that generates a current controlsignal, wherein the current mirror circuit increases an operatingcurrent thereof in response to a first transition of the current controlsignal and decreases the operating current in response to a secondtransition of the current control signal, and the control circuitincludes a slew-rate processing unit that controls a slew-rate of thecurrent control signal so that a first slew rate of the current controlsignal related to the first transition is greater than a second slewrate of the current control signal related to the second transition. 2.The semiconductor device as claimed in claim 1, wherein the internalvoltage generating circuit generates the second voltage when an activesignal is activated, the control circuit further includes a one-shotsignal generating unit that generates a one-shot signal that isactivated for a predetermined period in response to an activation of theactive signal, and the slew-rate processing unit controls the slew-rateof the current control signal having the first slew rate greater thanthe second slew rate by using the one-shot signal having a smaller slewrate in a transition from an active state to an inactive state than aslew rate in a transition from the inactive state to the active state.3. The semiconductor device as claimed in claim 2, wherein the one-shotsignal is a NAND signal of the active signal and a delayed signal of theactive signal.
 4. The semiconductor device as claimed in claim 2,wherein the slew-rate processing unit includes: an output terminal thatoutputs the current control signal; a first capacity element connectedbetween the output terminal and a first node; a first transistor and aresistive element connected in series between the output terminal andthe first node, the one-shot signal being supplied to a controlelectrode of the first transistor; and a second transistor connectedbetween the output terminal and a second node, the one-shot signal beingsupplied to an control electrode of the second transistor.
 5. Thesemiconductor device as claimed in claim 2, wherein the slew-rateprocessing unit includes: an output terminal that outputs the currentcontrol signal; a first capacity element connected between the outputterminal and a first node; a first transistor and a constant currentcircuit connected in series between the output terminal and the firstnode, the one-shot signal being supplied to a control electrode of thefirst transistor; and a second transistor connected between the outputterminal and a second node, the one-shot signal being supplied to acontrol electrode of the second transistor.
 6. The semiconductor deviceas claimed in claim 1, further comprising: a resistive element connectedbetween a non-inverting input terminal of the operational amplifier anda first node; a constant current circuit that supplies a predeterminedcurrent to the non-inverting input terminal, the predetermined currenthaving a current value obtained by dividing a target voltage of thesecond voltage by a resistance value of the resistive element; and aninternal circuit that operates on the second voltage generated by theinternal voltage generating circuit as a power source, wherein theinternal voltage generating circuit, the internal circuit, the constantcurrent circuit and the resistive element are formed in a single chip,and the internal voltage generating circuit, the internal circuit andthe resistive element are connected to the first node via a common lineprovided outside the chip.
 7. The semiconductor device as claimed inclaim 6, further comprising a capacity element connected in parallelwith the resistive element.
 8. The semiconductor device as claimed inclaim 1, wherein the internal voltage generating circuit includes afirst transistor of a first conductivity type having a control electrodeconnected to an output node of the operational amplifier, a firstcontrolled electrode supplied with the first voltage, and a secondcontrolled electrode outputting the second voltage, and the currentmirror circuit includes a pair of second transistors of a secondconductivity type, each of the second transistors having a controlledelectrode supplied with a third voltage that is higher than the firstvoltage.
 9. The semiconductor device as claimed in claim 1, wherein theinternal voltage generating circuit includes a first transistor having acontrol electrode connected to an output node of the operationalamplifier, a first controlled electrode supplied with the first voltage,and a second controlled electrode outputting the second voltage, and thecurrent mirror circuit includes a pair of second transistors of the sameconductivity type as the first transistor, each of the secondtransistors having a controlled electrode supplied with the firstvoltage.
 10. The semiconductor device as claimed in claim 1, wherein theoperational amplifier includes: a first current supplying transistorthat supplies the operating current to the current mirror circuit basedon a potential of the active signal; and a second current supplyingtransistor that supplies the operating current to the current mirrorcircuit based on a potential of the current control signal, wherein thefirst and second current supplying transistors are connected inparallel.
 11. The semiconductor device as claimed in claim 1, furthercomprising an additional internal power voltage generating circuit thatgenerates the second voltage from the first voltage regardless ofwhether an active signal is activated or not, wherein an output node ofthe additional internal power voltage generating circuit is connected toan output node of the internal power voltage generating circuit.
 12. Asemiconductor device comprising: an internal voltage generating circuitincluding a differential amplifier having first and second input nodesand an output node, first and second current supplying transistorsconnected in parallel to the differential amplifier to supply anoperating current to the differential amplifier, and a driver transistorhaving a control electrode and first and second controlled electrodes,the first controlled electrode of the driver transistor being suppliedwith a first voltage, the second controlled electrode of the drivertransistor being connected to the second input node of the differentialamplifier, the control electrode of the driver transistor beingconnected to the output node of the differential amplifier, the firstinput node of the differential amplifier being supplied with a targetvoltage of a second voltage to be generated, thereby the second voltageis output from the second controlled electrode of the driver transistor;and a control circuit that generates an current control signal based onan active signal indicating an activate period of the internal voltagegenerating circuit, the current control signal being activated for apredetermined period in response to a start of the activate period,wherein the active signal is supplied to a control electrode of thefirst current supplying transistor, the current control signal issupplied to a control electrode of the second current supplyingtransistor, and the control circuit includes a slew-rate processing unitthat makes a slew rate of the current control signal upon aninactivation thereof be smaller than a slew rate of the active signalupon an activation or an inactivation thereof.
 13. A method ofcontrolling a semiconductor device comprising: providing thesemiconductor device comprising an internal voltage generating circuitincluding an operational amplifier having a current mirror circuit, theinternal voltage generating circuit receiving a first voltage togenerate a second voltage; increasing an operating current flowing tothe current mirror circuit by activating a current control signal at afirst slew rate; and decreasing the operating current flowing to thecurrent mirror circuit by inactivating the current control signal at asecond slew rate, wherein the second slew rate is smaller than the firstslew rate.
 14. The method of controlling a semiconductor device asclaimed in claim 13, wherein the internal voltage generating circuitgenerates the second voltage from the first voltage when an activesignal is activated, and the decreasing the current includes: generatinga one-shot signal that is activated for a predetermined period inresponse to an activation of the active signal; and generating thecurrent control signal having the second slew rate smaller than thefirst slew rate by making a slew rate of an inactivated one-shot signalbe small.
 15. The method of controlling a semiconductor device asclaimed in claim 14, wherein the generating the one-shot signal isperformed by generating a NAND signal of the active signal and a delayedsignal of the active signal.
 16. The method of controlling asemiconductor device as claimed in claim 14, wherein the generating thecurrent control signal makes the slew rate of the inactivated one-shotsignal be small by charging a capacity element while the one-shot signalis in an active state and starting to discharge the capacity element ata timing when the one-shot signal is inactivated.